Formation chip sampling method

ABSTRACT

Formation chip sampling method for separating solids from the liquid contained in drilling mud which has been obtained from an earth boring operation. The returned drilling mud is flow connected in series relationship to a gas separator, a splitter which reduces the amount of sample to be treated, and to a reservoir. A pump flow connects the reservoir to a cyclone type separator which removes the solids from the sample. The reservoir further includes a level controller which provides make-up liquid so as to provide the pump with optimum suction conditions.

' United States Patent ['1 Elenburg FORMATION CHIP SAMPLING METHOD [76]Inventor: Wayland D. Elenburg, Box 1588,

Monahans, Tex. 79756 [22] Filed: May 22, 1972 [21] Appl. No.1 255,727

Related US. Application Data [62] Division of Ser. No. 4,546, Jan. 21,1970, Pat. No.

[52] US. Cl. 175/66, 175/206 [51] Int. Cl E2lb 21/00 [58] Field ofSearch 175/50, 60, 58, 59,

[56] References Cited UNITED STATES PATENTS 3,016,962 l/1962 Lummus etal. 175/66 3,494,188 2/1970 Boatman 175/50 X 2,225,973 12/1940 Brown eta1. 175/66 X 2,301,371 11/1942 Corwinn, 175/206X [451 Nov. 27, 19732,919,898 1/1960 Marwil et al 175/66 2,923,151 2/1960 Engle et al....175/206 X 2,941,783 6/1960 Stinson 175/206 3,039,545 6/1962 Rogers175/66 2,167,393 7/1939 Muncy 175/60 Primary Examiner-David H. BrownAttorney-Marcus L. Bates [57 ABSTRACT Formation chip sampling method forseparating solids from the liquid contained in drilling mud which hasbeen obtained from an earth boring operation, The returned drilling mudis flow connected in series relationship to a gas separator, a splitterwhich reduces the amount of sample to be treated, and to a reservoir. Apump flow connects the reservoir to a cyclone type separator whichremoves the solids from the sample. The reservoir further includes alevel controller which provides make-up liquid so as to provide the pumpwith optimum suction conditions.

3 Claims, 8 Drawing Figures PATENTEUNUYZYIHH v 3 774 FIG. 3

PATENTEDNUVZT 191s BOREHOLE FIG. 8

I FORMATION CHIP SAMPLING METHOD application Ser. No. 004,546 filed Jan.21, 1970, now

U.S. Pat. No. 3,664,440 issued May 23, 1972.

BACKGROUND OF THE INVENTION In thechip drilling process, dualconcentrically arranged ,drill pipe are connected between a drill bitand a swivel with drilling fluid flowing to and from the bit incounter-current relationship in order to cool and lubricate the drillpipe and bit and to remove chips and other cuttings from the bottom ofthe borehole by circulating the cuttings to the surface of the groundwhere the cuttings subsequently may be studied by geologists in order todetermine the physical and chemical properties of the strata of theearth through which the borehole has been formed. At the bottom of theborehole the drilling fluid picks up or entrains the chips and cuttingsand transports them upwardly within the central pipe, or alternatively,transports them upwardly within the annulus formed by the drill pipe,where the cuttings ultimately flow to the surface of the earth, all ofwhich is known to those skilled in the art; as evidenced by W.D.Elenburg, U.S. Pat. No. 3,439,757 to which reference is made for furtherbackground of the invention.

Retrieving representative core samples, reducing the core samples to aconvenient size which is conductive to studyv thereof, and relating thesamples to the specific depth of the borehole from which they originatedis extremely important in order for the geologist to carry out properanalysis of the various strata encountered. V

Heretofore it has been customary for others to flow connect the entiredrilling mud flow stream from the borehole to a flow divider apparatuswhich separates the major flow stream into several flow paths so as togreatly reduce the volume of the drilling mud or chip bearing flowstream which is to be treated for subsequent analysis. Often the flow isimproperly divided due to the physical characteristics of the solids andthe mechanics of the flow divider, all of which results in inaccurateanalysis of the borehole for the reason that one divided flow streamdiffers in composition or mixture from another divided flow stream.After the mud sample has been reduced in volume by selecting one of theflow streams for analysis, it is necessary to permit the solids tosettle by gravity, after which the clarified water is siphoned off ordecanted, and the remaining saturated solids or residue heated toevaporate the liquid therefrom.

It is therefore desirable to be able to split a stream of drilling mudcontaining samples from the chip drilling process into any desiredfraction of the main flow stream wherein the smaller fraction of themain flow is identical in-composition or mixture to the remainder of theflow. It is also desirable to be able to treat this fraction of flow inan improved manner which removes the solids therefrom, and to be able torelate the retrieved solid samples to the particular depth of theborehole from which the sample originated.

SUMMARY OF THE INVENTION This invention relates to formation chipsampling method for separating solids from drilling mud which may beobtained from an earth boring operation so as to enable subsequentanalysis thereof. As the drilling mud flows from the borehole, it exitsat the swivel and flows to a separator where the air is removedtherefrom. From the separator the flow continues to a splitter where afraction of the flow is separated from the main flow. The fractionalflow continues to a reservoir with the reservoir having fluid levelcontrol means associated therewith for supplying makeup water thereto inorder to always maintain a fluid level therein. The contents of thereservoir is pumped under a positive pressure to a cyclone separator.The, pump flow and the physical dimensions of the cyclone separator aresized with respect to one another so as to provide an optimum separationof solids from the liquid at the cyclone separator. Where deemeddesirable, and especially when utilizing the chip drilling process, ascreen may be interposed between the splitter means and the reservoir soas to reduce the load on the pump while at the same time maintaininglarge chips in an undamaged condition which will enhance the subsequentanalysis thereof. The screened solids are combined with the solidsremoved from the cyclone separator and placed in a suitable containerfor storage or shipment.

It is therefore a primary object of this invention to provide a methodof obtaining formation chip samples by separating solids from drillingmud.

Another object of the present invention is the provision of a method ofobtaining a fraction of the flow obtained from a borehole formingoperation which is representative of the main flow; and of separatingthe solids from the liquid contained in the fractional flow.

A still further object of the present invention is the provision of amethod by which formation chip samples are obtained from a chip drillingoperation by improvements in separating solids from the drilling mud.

A still further object of the present invention is the provision offormation chip sampling methods which removes air from drilling mud,separates the drilling mud flow stream into a fractional part whereinthe fractional part contains solids which are representative of thesolids contained within the main flow stream, and which separates thesolids from the liquid of the fractional component of the main stream.

Still another object of the present invention is a method of removingsolids from drilling mud so as to provide a formation chip sample whichcan be related to the particular depth of borehole from which the sampleoriginated.

The above objects are attained in accordance with the present inventionby the provision of method and apparatus for obtaining formation chipsamples as set forth in the above abstract and summary.

Various other objects and advantages of this invention will'becomereadily apparent to those skilled in the art upon reading the followingdetailed description and by referring to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. I is a part diagrammatical, partschematical representation in the form of a flow sheet which describesthe essence of the method of the present invention;

FIG. 2 is a side elevational view of apparatus previously seen in FIG.1;

' FIG. 3 is a top plan view of the apparatus disclosed in FIG. 2;

FIG. 4 is a top plan view of part of the apparatus seen in FIG. 1, withsome parts thereof being diagrammatically illustrated by dot-dash lines;and

FIG. 5 is a cross-sectional view taken along line55 of FIG. 4, with someparts thereof being unsectioned for clarity;

FIG. 6 is a part diagrammatical, part schematical representation in theform of a flow sheet which describes another embodiment of the presentinvention;

FIG. 7 is an enlarged, part cross-sectional view, taken along line 7-7of FIG. 6; and

FIG. 8 is a reduced top plan view of a part of the apparatus disclosedin FIG. 6, with some parts thereof being broken away therefrom in orderto better disclose the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT As seen in thediagrammatical representation of FIG. 1, the present invention is usedin conjunction with a borehole forming operation, broadly indicated bythe arrow at numeral 10, wherein there is seen concentrically arrangeddrill pipe extending into the ground with the upper terminal end thereofbeing connected to a swivel 12. Drilling fluid, or drilling mud ispumped to the swivel in the usual manner while drilling fluid containingchips and particles of the formation being penetrated are retrieved atgooseneck 16. The gooseneck is flow connected to tangential inlet 17 ofair separator means 18. The air separator has an upwardly dependingcentrally located conduit 19 from which air escapes. The air-free liquidflows through bottom outlet 20 and is directed into a splitter means 21.

The splitter includes a large outlet 22 which is flow connected to mudpit 23 by any suitable means, and to which the major portion of the flowis conducted. Small outlet 24 receives the remaining fraction of thedrilling mud which is originally returned from the borehole. Theremaining portion or fraction of the mud flows through screen 25 inorder to remove large particles or chips therefrom. The fraction of thedrill fluid which includes the smaller cuttings or particles which werenot retained by the screen continues to flow on to the reservoir at 26.The upwardly opening reservoir has a sloped bottom to which a loweroutlet is flow connected to pump means 27.

The pump can be actuated by any suitable means, as for example, agasoline motor. The pump provides a high pressure flow to tangentialinlet 28 of cyclone separator 29. As the drilling fluid flows throughthe cyclone separator, the liquid is separated from the remaining solidscontained therein, with the liquid finally exiting at 30 where it can beflow connected to any suitable disposal means, as for example, the mudpit, while solids fall through lower outlet 31 where they are retrievedwithin any suitable receptacle 32. A source of makeup water (not shown)is connected to valve means 33 which in turn is controllably flowconnected to a journaled float means 34 by the illustrated linkage. The

float and valve assembly provides a level controller device forcontrolling the flow of make-up water into the reservoir so as tomaintain a suction for the pump at all times.

FIGS. 2 and 3 show the details of the separator apparatus which includesa gear driven pump 27 having rubber impellers thereon and which iscapable of producing a flow rate and pressure consistent with the designof cyclone separator 29 and to the mud flow rate into the reservoir.

The reservoir is provided with a means for maintaining a fluid leveltherein, preferably in the form of a styrofoam float 34 which has asupport arm depending therefrom and journaled to any convenientstructure, as for example a side wall of the reservoir. The arm isconnected by linkage 33' to the valve means 33 so as to actuate thevalve as the fluid level within the reservoir changes. The valve meanshas an inlet which is flow connected to any suitable source of make-upwater and an outlet into the trough. The valve means can alternativelybe connected to flow directly into the outlet of the reservoir if deemeddesirable.

The pump is driven by an internal combustion gasoline motor of thefollowing described type: Wisconsin Engine, 3 X 3% size. The pump is ofthe following described type: gear driven, rubber impellers, capable of40 g.p.m. at 9-l5 p.s.i.g., manufactured by Booie. The inlet of thecyclone separator is provided with 40 g.p.m. flow rate. The separator isavailable from Kerbs Engineering, 1205 CryslerDrive, Menlo Park,California, Model D4B-l 2.

Looking now to the details of FIGS. 4 and 5, the before mentioned airseparator 18 is seen to be in the form of a cylindrical tub havingtangential inlet 17 connected to an upper extremity of the sidewallthereof; and with an upwardly depending reduced diameter air outlet 19being provided at the upper end thereof. Outlet 20 is in the form of adownwardly and outwardly directed elbow which is arranged in overhangingrelationship with respect to the splitter so as to cause the mud flowingtherefrom to impinge against the rotating vanes of the splitter, as willbe pointed out in greater detail later on.

The splitter has an upwardly opening interior as indicated by the arrowat numeral 35 which is formed by the stator of fixed tub portion 36.Within the stator there is rotatably disposed a rotor comprised ofcylinder 37 having a multiplicity of radially disposed vanes 38 whichrigidly connect the cylinder to a tubular element 39. The tubularelement is rigidly affixed to a shaft 40 with the shaft having spacedapart bearings 41, 42, each of which are located at the upper and lowerextremity of the shaft so as to rotatably support the shaft from thefixed members 43 and 44. Tubular member 39 is received within theupwardly opening complementary fixed tubular member 45. inwardly slopedfloor members 46, 48 are affixed between adjacent vanes and form spacedapart catch basins between some of the vanes, with the lower extremityof the basins being apertured as seen at 49 so as to communicate theinterior of the complementary fixed tubular member therewith.

A pair of spaced apart rails 51 underlie the trough 24 and provides asupport means for the before mentioned screen so as to enable the screento be conveniently interposed between small outlet 24 and the reservoir.While the particular embodiment disclosed herein illustrates each sixtharea as being a basin it is preferred that each fourth area betweenadjacent vanes be provided with a lower bulkhead or floor so as toprovide the before mentioned split of 25 percent of the flow.Alternatively, othe rsplits may be achieved by merely varying the numberof floor members employed within the rotor.

Valve 133 is actuated by float level device 134 in a manner similar tothe arrangement of the level controller disclosed in FIGS. 1-5. Outlet160 is connected to a bypass T 161, with the T having the illustratedvalve therein for flowing mud to the mud pit. Valve 162 connects the Tto pump 127, which in turn is connected to inlet 128 of separator means129.

The separator has a liquid outlet I30 and a solids outlet 131.Receptacle 132 can be any suitable container for receiving core samplesfrom the separator means.

The liquid outlet 130 is freely received within the inlet elbow 163 ofstorage tank 165 with the outer peripheral wall surface of the outletbeing spaced apart from the inner peripheral wall surface of the elbow.Overflow 164 can be flow connected to the mud pit, and is located belowthe inlet of the elbow so as to maintain the liquid height within thetank at a level which always leaves room for liquid flow from theseparator. Outlet 166 is flow connected to the valve 133 of the liquidlevel control means.

OPERATION In operation, drilling mud is circulated from a main mud pump(not shown), to the swivel where it is forced through the drill stringannulus downhole to the drill bit, and back through the centralpassageway to the inlet 17 of the air separator. The formation samplescut by the action of the bit are in the form of chips and cuttings, andare transported by the drilling fluid into the air separator 18. The airseparator can take on several different forms but preferably is similarto a centrifuge in that a vortex is established by the tangental inlet17, thereby causing the drilling fluid tobe separated from air containedtherewithin. The air separator is especially useful where the chipdrilling process is supplemented with air drilling, but is notconsidered indispensable to the process. As drilling mud exits fromoutlet 20, it impinges against the vertically disposed radiating vanesof the splitter, causing a rotational motion to be imparted into therotor. Since the rotor is spaced apart from the wall of the stator andjournaled at its upper and lower extremity, it will rotate at a r.p.m.or with a peripheral velocity which is dependent upon the flow rate ofthe drilling mud received therewithin. The major portion of the mud flowstream is free to flow through the spaced apart vanes at 47' and to theoutlet 22, while a smaller fraction thereof is intercepted by the catchbasins formed by the floor members 418.

As the mud flows through the spaced apart vanes 38, that is, theadjacent vanes which have no floor therebetween, it continues on throughthe rotor and into the lower extremity of the tub or stator where itthen flows through outlet 22 and is directed to the mud pit 23. Thesmaller fraction of the drilling mud which flows into the catch basin,however, is trapped by the floor member and diverted through apertured9, into the rotatable tubular member, and into fixed tubular member455,

where it then flows from lower chamber 50 and through outlet 24.

The number of catch basins 48 may be varied to provide any splitdesired, as for example, one sixty-fourth or one-half of the totalreturned mud flow may be deemed desirable as a feed rate into thereservoir 26. The number of catch basins determines the formation samplesize as well as the load placed on the screen, reservoir, pump, andcyclone.

Trough 24 preferably is arranged in overhanging relationship withrespect to reservoir 26 so as to enable fluid therefrom to flow bygravity thereinto. Screen 25 is preferably of 60 mesh size and isinterposed between trough 24 and the reservoir by merely resting theedge portions of the screen on the spaced apart support members 511 asgenerally indicated by the arrow at numeral 25'.

Since most chip drilling operations employ a fluid circulation rate ofabout gallons per minute when making a 4 /2 inch diameter hole, it isevident that the fraction of this amount which will be divided out bythe splitter and received within the reservoir is dependent upon theratio of catch basins to the open vanes. Since the pump 27 preferablyreceives exactly 40 gallons per minute, and assuming a 25 percent split,it is evident that the float 34 must open valve 33 a sufficient amountto supply 5 gallons of fresh make-up water per minute in order tomaintain a fluid level within the reservoir.

Pump 27 delivers a constant flow of fluid to, the cyclone separator,which can take on several different forms, and preferably is essentiallya vertical cylinder with the usual inlet stream 28 being introducedtangentally near the top so as to give a spinning motion to the liquidtraveling therethrough. The centrifugal force acting on the suspendedsolids tends to throw them radially to the side of the cyclone as thesolids spiral downward to the conical bottom where they are removed at31. The separated liquid is disposed of at the top, with the conduit 30being a conventional outlet. With the cyclone separator operating withinits most efficient range, essentially no liquid is lost through thesolids outlet and essentially saturated solids drop into the receptacle32. It is for this reason that the pump 27 must always operate withinits most efficient range, or otherwise the operation of the cyclone willnot produce this desired effect.

The cyclone effectively removes all of the suspended solids. In oneseries of test carried out in accordance with the present method, onehalf gallon of 60 mesh sand was introduced into the reservoir, andseparated by the cyclone with five passes through the separator portionof the equipment being made. The accumulated loss of sand during thesefive passes was negligible, being on the order of 1 percent loss.

The sample attained at 32 is related to the borehole depth by changingthe screen 25 and receptacle 32 each five foot of hole, although otherincrements of penetration may be used where deemed desirable. Since thesplitter divides out any desired portion of the returned mud, and sincethe divided portion of the flow stream is identical in composition tothe remainder thereof, the present invention provides formation sampleswhich are more representative of the strata being penetrated than hasheretofore been possible to attain. All of the suspended solids passingthe screen 25 are effectively separated from the liquid in a mannerwhich obviates the necessity of decantation and evaporation treatment ashas heretofore been necessary with prior art devices. By utilizing thepresent invention, each time the screen and receptacle is changed forthe next five foot sample, it is now possible to immediately bag theobtained core sample and send it to the geologist. Accordingly, possiblecontamination of the sample is avoided since it is exposed a minimumlength of time to the elements. This also avoids inadvertent interchangeor mix-up of the samples.

This combination of equipment is rugged, inexpensive, and provides theunexpected advantage of enabling relatively liquid free samples to beobtained at outlet 31. The term liquid free formation sample is intendedto mean samples which are saturated in liquid but which requiressubstantially no decantation or evaporation in order to be sealed andtransported to the geologist.

In carrying out the invention in accordance with the embodimentdisclosed in FIGS. 6-7, the large cuttings are obtained on screen 125and combined with th centrifuged solids obtained at 132. The use of asplitter downstream of air separator 118 is considered optional,depending upon the flow rates involved. While making hole through knownstrata, the valve at 161 can be opened, while valve 162 is closed, so asto flow all of the mud to the mud pit, thereby leaving the pump andcentrifuge inactive until they are needed.

When a mineral bearing strata is encountered, the valve at 161 isclosed, the valve at 162 opened, and circulation through pump 127initiated. Mud now flows into the air separator, through the screen, andinto the reservoir. Make-up water flows from 166, 133 and throughtangential inlet 167 where the side walls of the reservoir are cleanedof cuttings. The float at 134 main tains a fluid level within thereservoir which enables the pump to provide the separator means with aconstant flow so as to achieve optimum efiiciency of separation.

The liquid outlet from the separator is freely received within the elbow163 of the make-up water storage tank so as to prevent back pressure onthe separator which could adversely affect its operation.

Since the overflow pipe 164 is located below the inlet elbow, thestorage tank will overflow to the mud pit without affecting the liquidflow from the separator. Outlet 166 provides a constant source ofmake-up water to valve 133. Since the solids have been removed from thedrilling mud, the only contaminate which can the addition of any make-upwater which may be required for maintaining a proper fluid level withinthe make-up tank. This modified flow system is especially useful wherewater is at a premium.

The present invention provides a method of obtaining formation chipsamples which permits both a qualitative as well as a quantitativeanalysis to be achieved since the weight percent of any materialobtained in a formation chip sample can be directly related to the totalamount of material removed from the borehole. This aspect of theinvention is particularly important relative to ores such as copper andmolybdenum, for example, since the economical breaking point ofmolybdenum is at about 0.5 percent, and accordingly 0.1 percent accuracyis very important when making a chemical analysis of the formation chipsample in order to determine the economics of sinking a mine shaft.

The specific splitter means together with the cyclone separator usedherein is indespensible for handling ores which tend to float due totheir surface tension and particle size. Material of this nature wouldotherwise be lost because they would float off to the mud pit in theabsence of the present method.

While a particular pump and cyclone separator have been disclosed hereinfor purposes of illustration, it is pointed out that other pumps andother types of cyclone separators or centrifuge means may be used solong as the inlet pressure and flow rate to the cyclone separator ismaintained within a range which prevents liquid from falling from theseparator into the receptacle, and so long as carry-over of solids intothe discharge is avoided.

I claim:

I. In a borehole forming operation wherein liquid is used to circulateformation chips formed by the drill bit from the bottom of the boreholeto the surface of the earth during the drilling operation, the method ofobtaining formation chip samples comprising the steps of:

dividing the liquid bearing the formation chips flowing from theborehole into a plurality of equal flow paths; flowing one of saidplurality of flow paths into a reservoir, and continuously pumping thematerial contained in the reservoir into a cyclone type separator toseparate the chip samples from the liquid;

maintaining said continuous flow rate to said separator by addingmake-up liquid to the reservoir in an amount as needed to maintain aconstant liquid level in the reservoir.

2. The method of cliam 1 wherein said one of the flow paths is flowconducted through a screen so as to remove part of the formation chipsamples therefrom prior to the separation step of the cyclone separator.

3. The method of claim 1 wherein the spent liquid from the cycloneseparator is recirculated to the reservoir to provide for the make-upliquid.

1. In a borehole forming operation wherein liquid is used to circulateformation chips formed by the drill bit from the bottom of the boreholeto the surface of the earth during the drilling operation, the method ofobtaining formation chip samples comprising the steps of: dividing theliquid bearing the formation chips flowing from the borehole into aplurality of equal flow paths; flowing one of said plurality of flowpaths into a reservoir, and continuously pumping the material containedin the reservoir into a cyclone type separator to separate the chipsamples from the liquid; maintaining said continuous flow rate to saidseparator by adding make-up liquid to the reservoir in an amount asneeded to maintain a constant liquid level in the reservoir.
 2. Themethod of cliam 1 wherein said one of the flow paths is flow conductedthrough a screen so as to remove part of the formation chip samplestherefrom prior to the separation step of the cyclone separator.
 3. Themethod of claim 1 wherein the spent liquid from the cyclone separator isrecirculated to the reservoir to provide for the make-up liquid.